docs: def play_Track(self, track, channel=1, bpm=120):
          """Play a Track object."""
          self.notify_listeners(self.MSG_PLAY_TRACK, {'track': track, 'channel'
                                : channel, 'bpm': bpm})
          for bar in track:
              res = self.play_Bar(bar, channel, bpm)
              if res != {}:
                  bpm = res['bpm']
              else:
                  return {}
          return {'bpm': bpm}